Speedometer

vehicles · how it works · invention

Tells you speed. A speedometer shows the instantaneous speed of a vehicle, meaning the exact speed at that very moment. It's now on every car, truck, and motorcycle.

Became standard early on. Speedometers started as optional extras in the early 1900s, but by around 1910 they became standard equipment on most motor vehicles.

Different vehicles, different devices. Boats don't use speedometers like cars do. Instead, boats use a pit log to measure speed, while airplanes use an airspeed indicator to show how fast they're flying through the air.

Essential safety tool. Knowing your speed helps drivers stay safe and follow speed limits. Without a speedometer, you'd have no idea if you were going too fast or too slow.